CN1542781A - Playback and recording device with tilt control system for optical recording media - Google Patents

Abstract

The invention relates to a method and an arrangement for a replay or recording appliance for optical recording media having an inclination control system for vertical alignment of the scanning beam with respect to optical recording media. In order to exclude other factors which, in addition to the inclination of the scanning beam, influence the radio-frequency signal which is detected by the recording medium, without any additional inclination sensors from the disadvantageous influence of the inclination control, an inclination control system is provided which uses the lower envelope curve signal of a radio-frequency signal which is detected by the optical recording medium and represents the dark value of the detected radio-frequency signal. The lower envelope curve signal is multiplied upstream of an inclination control system by a modulation signal which is added to the output signal from the inclination controller for vertical alignment of the scanning beam which is directed at the optical recording medium. The envelope curve signal which is, for example, the mirror signal is multiplied by the modulation signal and is integrated or low-pass filtered in order to form a control error, which corresponds to an error between the scanning beam, which is directed at the optical recording medium, and the vertical.The invention is intended to be used for replay or recording appliances for optical recording media with inclination control.

Description

Playback and recording apparatus with tilt control system for optical recording media

technical field

The present invention relates to a method and structure of a playback and recording device for optical recording media having a tilt control system that aligns a scanning beam in at least one direction at a right angle, such as for CD, DVD or Blue The optical recording medium of the disc (Blue Disc).

Background technique

Optical recording media such as CDs, DVDs, or Blue discs are often radially curved outwards, upwards, or downwards, and by conventional scanning devices that guide the scanning beam exclusively on the track and in the focus direction of the recording medium, it is impossible to record or play back. This applies especially to recording media consisting of a large number of layers, such as DVDs. A recording medium that is curved from the inside to the outside due to the curvature is also called an umbrella disk. The surface of a disk such as this can be tilted, also called radial tilt for a plane, so the scanning device or actuator must be tilted so that the scanning beam is aimed at the recording medium at right angles, because only when the scanning beam is aligned at a right angle Optimum recording or playback of information can only be ensured when using the correct recording medium. Recording medium flexing, denoted in German as Plattenschlag [disk impact], is repeated with each rotation of the recording medium, usually resulting in radial and tangential tilting.

An apparatus has been disclosed in US-A-5034939 for directing the scanning beam at a right angle to the recording medium by tilting the scanning means. In such devices, the error rate in the data signal read from the recording medium is used for alignment at right angles, and/or in order to change the tilt of the scanning beam. The smallest error rate in this case corresponds to the best skew correction. Furthermore, a tilting servo circuit is known from US-A-5001690, by which the tilting angle of the scanning beam is varied in order to achieve a maximum electric potential of the reproduced information signal or the HF signal detected from the recording medium. flat.

However, the error rate and level of the HF signal depends not only on the skew, but also on a large number of other factors such as scratches, so-called black spots, pit depth, degree of reflectivity of the disc and any focus shift. However, in addition to the tilt of the scanning beam, scratches and other factors affecting the detected RF signal lead to unnecessary correction of the tilt angle, which has the effect of being a deviation from aligning the recording medium at right angles. The resulting, adverse effect on the scanning or recording of information.

Also, the direction of the tilt angle change is only determined after the previous change to the tilt angle and after the error rate or HF level has increased or decreased, so an incorrect direction may be chosen first and it is not possible to correct the tilt angle immediately. In addition, the central processing unit of the device is utilized to determine the direction of the change in tilt angle as a function of an increase or decrease in error rate or HF signal level. In addition to the tilt of the scanning beam, an additional tilt sensor is also used for tilt control in order to exclude from the tilt control processor those factors that affect the detected RF signal, but this involves additional complexity.

Contents of the invention

It is an object of the present invention to provide a method and structure of a playback or recording device for optical recording media with a tilt control system which substantially overcomes the above-mentioned disadvantages and which can be implemented uncomplicated and without any additional tilt sensor.

This object is achieved by the features indicated in the independent claims. Advantageous refinements are specified in the dependent claims.

An aspect of the invention is to direct the scanning beam of a playback or recording device for an optical recording medium at right angles to the recording medium without requiring any additional sensors and largely unaffected by the detected beam except for the tilt of the scanning beam. The influence of other factors of the radio frequency signal. The scanning beam used for recording or reproducing information is subordinated to the deviation of the recording medium from the plane by a tilt control system, or the scanning device generating the scanning beam is aimed at the recording medium at right angles if any tilting or tilting occurs. The advantage of aligning the scanning device at right angles to the recording medium by means of a tilt control system is that, in addition to improving recording or playback, adjustments to the scanning device during production of the recording or playback device can be performed with less precision. And the object of the present invention is also to detect as high radio frequency signal as possible from the recording medium by aiming the scanning beam at right angles to the recording medium, however, apart from the tilt of the scanning beam, influence on the radio frequency signal should be excluded from the control of the scanning beam tilt other factors of amplitude and/or level. Another object is to avoid additional tilt sensors and control processes according to the so-called trial and error principle.

Accordingly, a tilt control system is provided which is based on a lower envelope signal or mirror image signal of a radio frequency signal detected by an optical medium and corresponding to the dark of the radio frequency signal detected from the optical recording medium. value (dark value). The lower envelope signal or mirror signal is multiplied by a modulation signal and integrated to form a control error corresponding to the tilt of the scanned beam with respect to the optical recording medium. A modulating signal is also added to the signal for controlling the means for adjusting the tilt of the scanning beam directed at the optical recording medium, said modulating signal is, according to an exemplary embodiment, a square wave signal with a signal phase at zero or Change polarity after stopping. In one embodiment, the amplitude of the modulation signal is selected so as to cause a change in tilt of the scanned beam of approximately 1/30 degree or 2 arc minutes. According to an exemplary embodiment, a symmetrical square wave signal with a frequency of 4 Hz, with a defined amplitude and 50% zero component is used as the modulating signal. In principle, however, other signal forms, such as sinusoidal, triangular or sawtooth signals, can also be used as modulation signals. As for the frequency, it is advantageous to have a modulation signal with a duration corresponding to at least one revolution of the recording medium, although other frequencies may also be used taking into account the need to tilt the speed of the control system.

Since the tilt control is performed using the lower envelope signal or dark value of the radio frequency signal detected from the recording medium, this prevents other factors that also affect the amplitude and/or level of the radio frequency signal detected from the recording medium from affecting the tilt control adverse effects on the system. The modulation signal used for tilt control is selected so as to be virtually undetectable in the radio frequency signal detected from the recording medium. Since the tilt angle changes relatively slowly during the scanning of the recording medium, a lower modulation signal frequency is sufficient for tilt control. The lower envelope signal is multiplied by the modulating signal and then integrated to directly determine the control error representing the error in aiming the scanning beam at a right angle to the recording medium, resulting in dynamic and immediately effective tilt control.

To implement the method in a recording or playback device, already existing components can advantageously be used in such a device. For example, so-called mirror signal detectors have been provided in those devices for detecting track changes, which results in a lower envelope signal called the mirror signal. In this case, the mirror signal normally only used for the open track control loop when the scanning beam leaves the recording track is used for tilt control in the closed track control loop. To generate the tilt angle control loop, multipliers, modulators and tilt controllers are provided, so that a circuit configuration, for example in the form of a digital circuit configuration, can involve little complexity. The lower envelope signal generated by the envelope detector or the wobble detector is supplied to a multiplier connected to a modulator to generate a modulated signal. Multiplication of the envelope curve signal with the modulating signal results in a correlation of the envelope curve signal with the modulating signal such that integrating the signal over at least one period produces a control error which corresponds to the tilt and is provided to the tilt control The tilt controller is connected to a multiplier and its output is connected to a modulator and means for adjusting the tilt of the scanning beam. The output signal from the tilt controller is used in the actuator in order to drive the coil for scanning the tilt of the beam, which is equivalent to the coil for tracking or focusing, and has a comparable transfer function, thus allowing the above 100Hz Rapid tilt angle changes within the range. Due to the lower signal frequency, A/D and D/A converters can also be used in tilt control loops, which are used in recording of optical recording media with digital servo control loops. or provided in a playback device so as to control the scanning means and digitize the signals detected by the scanning means from the recording medium. The scanning beam can be directed at right angles to the recording medium using known 3D actuators, which are used to calibrate the tilt angle of the scanning beam with respect to the recording medium through coils or motors.

Although the recording medium normally used in recording devices still does not contain any recorded information for forming radio frequency signals in playback devices, the method and structure of the present invention can still be used in recording devices and playback devices because such as Such a recording medium has a wobbled track for recording information, which also generates a radio frequency signal which is detected by a wobble signal detector.

The proposed tilt control loop does not require any additional processor power, thereby eliminating the need to load a central processing unit to determine the direction of tilt angle change.

Description of drawings

In the following text, the invention will be explained in more detail with reference to exemplary embodiments in the accompanying drawings, in which:

Fig. 1 shows the block diagram that is used for the circuit structure of tilt control in the reproducing apparatus of optical recording medium;

Figure 2 shows a profile diagram regarding the alignment of the scanning beam for an upwardly curved recording medium;

Figure 3 shows a profile diagram regarding the alignment of the scanning beam for a downwardly curved recording medium;

Fig. 4 shows the profile diagram of the structure of related known optical scanning device;

Figure 5 shows a profile diagram relating to the alignment of the scanning beam of a known optical scanning device;

Figure 6 shows a profile diagram of the tangential tilt of the scanned beam with respect to the recording medium;

Figure 7 shows a profile diagram of the radial tilt of the scanned beam with respect to the recording medium;

8 shows a block diagram of a circuit configuration for tilt control in a recording apparatus for an optical recording medium;

Figure 9 shows a profile diagram illustrating scanning beam tilt;

Figure 10 shows a profile plot of the scan variation with scan beam tilt;

Figure 11 shows a graph of the relationship between the lower envelope curve and the tilt of the scanning beam;

Figure 12 shows a contour plot of a radio frequency signal for illustrating larger slopes;

Figure 13 shows the modulated signal;

Figure 14 shows a profile diagram for illustrating a radio frequency signal with reduced tilt;

Figure 15 shows the modulation signal;

Figure 16 shows a profile diagram for illustrating the radio frequency signal when the scanning beam is aligned at right angles; and

Fig. 17 shows the modulated signal.

Reference signs are used in a matching manner in the drawings.

Detailed ways

A recording or playback device for an optical recording medium has scanning means PU for scanning an optical recording medium OD, which is not shown in FIG. 1 . The scanning means PU are driven in a known manner by the tracking error signal TE and the focus error signal FE to track and focus the scanning beam on the optical recording medium OD. The light reflected from the optical recording medium OD is detected by the photodetectors A to F, and is transferred in a digital servo control loop via at least one of the analog/digital converter A/D and/or the signal generating device SG Provided to the controller to control tracking and focusing.

Furthermore, the scanning unit PU generates a radio frequency signal HF which is detected from the optical recording medium OD and corresponds to the light intensity. The reproduced information signal is formed by high-pass filtering the HF signal. The radio frequency signal HF is also supplied in a known manner to an envelope detector ENV for generating an upper envelope signal up corresponding to the intensity of a so-called land and a value of the radio frequency signal HF. Lower envelope curve signal lo. The lower envelope signal corresponds to the intensity of the pits.

These envelope curve signals up, lo are generally generated in a recording or playback device for the optical recording medium OD in order to be able to estimate track changes or disturbances on the optical recording medium OD, for example, with high reliability. The lower envelope signal lo is also called an image signal, and in the case of an open track control loop, the lower envelope signal is usually used to signal a track change. Thus, the representation of the mirror image and the mirror image signal is based on the scanning beam passing through the mirror image region of the optical recording medium OD during a track change.

The upper envelope signal up and the lower envelope signal lo generated by the envelope detector ENV from the radio frequency signal HF are illustrated in FIGS. 12 , 14 and 16 . Figures 12, 14 and 16 show a radio frequency signal HF having different levels or different amplitudes, which is affected by the tilt of the scanning beam with respect to the optical recording medium OD. For the tilt of the scanned beam with respect to the optical recording medium OD, as illustrated in Figures 6 and 7, a basic distinction between radial tilt and tangential tilt is drawn.

Figure 6 shows the tangential inclination of the scanning beam with respect to a recording track on the optical recording medium OD, where the inclination angle β of the scanning beam relative to the perpendicular of the optical recording medium OD is the tangential inclination angle β. The tangential tilt angle β results in pits with different lengths that may be read on the optical recording medium OD, and the radial tilt angle α results in a reduction in the level or amplitude of the radio frequency signal HF scanned from the optical recording medium OD. Since the inclination with respect to the scanning beam perpendicular to the optical recording medium OD causes a wider scanning spot, the level or amplitude of the radio frequency signal HF is reduced.

If the scan beam is assumed to be circular, an ellipse is reflected if there is any tilt. When the scanning beam is on a land, the ellipse corresponds exactly to the mirrored area, and the intensity of the scanning beam is relatively independent of tilt. When the scan beam is on a pit, then its intensity varies, since the optimum pit intensity or optimum dark value is achieved by cancellation only when the incident radiation is at right angles.

The scanning beam is focused on the optical recording medium through the focus control loop, so that as shown in Figure 10, when the scanning beam is aimed at the optical recording medium OD at a right angle, a Circular spot. The light reflected from the optical recording medium OD is detected by the scanning unit PU with a photodetector for the main beam of known structure (comprising four quadrants A, B, C, D) and two auxiliary Beam detectors E, F.

Usually the signals from the auxiliary beam detectors E, F are used to form the tracking error signal TE of the CD recording medium OD, while the difference signal between the sum of the phase quadrants of the main beam detectors is used to form the focus error signal FE, and using The sum signal of the quadrants A, B, C, D to form the information signal of the radio frequency signal HF. A focus control loop for a scanning unit PU such as that controls the objective lens of the scanning unit PU to a position so that a circular spot is always formed on the photodetector.

However, as shown in Figure 9, a scanned beam of width b directed at the optical recording medium OD at an oblique angle a and is reflected and detected illuminates an area of length a. This length a due to the radial inclination angle α results in a wider scanning spot having a length a relative to the information track width T of the optical recording medium OD.

However, the scanning of optical recording media OD with information storage elements consisting of depressions or projections, ie in the case of writable optical recording media OD the so-called The pits or so-called channels are formed so that a predetermined relationship must be maintained between the simultaneously illuminated protrusions and depressions in order to cancel the scanning beam reflected from the recording medium OD.

This relationship is disturbed if the scanning spot has a length a for the information track width T of the optical recording medium OD. A larger proportion of light is reflected from specular surfaces located between information tracks than from recesses or from information tracks. The wider scanning spot from the recording medium OD results in a lower dark value being detected due to the selection of the pits forming the information tracks on the optical recording medium OD so as to produce a phase shift which causes the scanning beams to cancel out. The maximum value of light reflected from the optical recording medium OD between tracks or conversely away from the pits of the recording medium OD remains constant.

The change between depressions and protrusions on the information carrier layer of the recording medium OD is detected by the scanning means PU as radio frequency signal HF. The subsequent reduction of the cancellation of the scanning beam reflected from the recording medium results in a radio frequency signal HF having a lower level or smaller amplitude, because the difference between the maximum value and the minimum value of the radio frequency signal HF is called the value of the radio frequency signal HF level or amplitude. The maximum value of the radio frequency signal HF forms an upper envelope signal up, and the minimum value of the radio frequency signal HF forms a lower envelope signal of the radio frequency signal HF.

Since the lower envelope signal lo represents the dark value of the signal detected from the recording medium OD, the ratio of the lower envelope Low Env to the maximum value AD-Max is at a minimum when the scanning beam is directed at the recording medium OD at right angles , as shown in FIG. 11 , said maximum value AD-Max is detected from the quadrants A...D of the photodetectors of the scanning means PU. The ratio of the error Tilt from aligning the scanning beam at right angles to the recording medium OD relative to the calibration Tilt without any error is taken as the abscissa of the graph in FIG. 11 . FIG. 11 thus shows the relationship between the lower envelope or the lower envelope signal lo and the radial inclination of the scanning beam with respect to the recording medium OD.

In order to achieve a radio frequency signal HF with the highest possible amplitude or at the maximum level, the scanning beam and the optical axis OA of the scanning device PU must always be aligned at right angles to the optical recording medium OD, even when the optical recording medium OD is bent So, as shown in Figures 2 and 3 . The curvature of the recording medium OD generally increases from an inner radius IDR through a middle radius MDR to an outer radius ODR, the optical recording medium OD may be curved upwards as shown in FIG. 2 or downwards as shown in FIG. 3 . Furthermore, it is also possible for the optical recording medium OD to be bent up to a specified radius, and then bent down, and vice versa.

However, the smallest curvature generally occurs at the inner radius IDR of the optical recording medium OD. For low storage density optical recording media OD such as CDs, initially it is neither intended nor necessary to obliquely align the optical axis OA of the optical recording media OD at right angles, so that the scanning device PU shown by way of example in FIG. 4 is enough. The optical scanning device PU as shown in FIG. 4 includes an objective lens OL mounted on a lens holder LH elastically supported on a wire holder WH via four metal wires. The terminal block WH is mounted on the base AP, which is also equipped with a magnet M. A focus coil FC and a tracking coil TC are placed on the lens holder LH and driven via wires SPW to deflect the objective lens in track and/or focus direction.

In a manner not shown, a laser and a photodetector for generating and detecting the scanning beam, respectively, are placed below the lens holder LH. The scanning device PU is usually placed on a coarse drive so that it can scan the optical recording medium OD over the entire area of the information carrier layer. As shown in Fig. 5, scanning devices PU such as these do not take into account any curvature of the optical recording medium OD.

The optical axis OA of the scanning device PU is aligned at right angles to the flat recording medium OD during the production process, and this alignment of the optical axis OA is also maintained during scanning of curved recording media by using parallel guide grooves formed by the wires SPW. allow. As shown in FIGS. 2 and 3 , in order to ensure that the optical axis OA is always aligned at right angles to the optical recording medium OD even in the case of a curved recording medium OD, it is known that in the scanning device PU, by means of a motor tilt The optical axis OA matches the curvature of the optical recording medium by placing the scanning device PU or obliquely placing the objective lens OL, as shown in FIG. 4 .

Additional coils are then provided in order to tilt the objective lens OL, by means of which the lens holder LH and the objective lens OL are additionally tilted in order to deflect the focus and track direction. Independently of the means for tilting the optical axis OA of the scanning device PU, a control loop is provided by which the optical axis OA is appropriately subordinated to the bending of the optical recording medium OD in order to always ensure that the scanning beam is directed at right angles to the The quasi-optical recording medium OD regardless of the curvature of the recording medium OD or whether it is placed obliquely when the scanning device PU is in the neutral position.

In order to avoid the disadvantages of known control loops for tilt control, a control loop using an envelope curve representative of the dark value of the radio frequency signal HF obtained from a scan of the optical recording medium OD is provided.

When considered in the normal way, this envelope is the envelope signal lo under the radio frequency signal HF detected from the information track on the optical recording medium OD. As shown in FIG. 12, if the scanning beam has a tilt that must be corrected relative to the recording medium OD, the lower envelope signal lo is relatively far from the reference line N and relatively close to the upper envelope up of the radio frequency signal HF.

As shown in a comparison of Figures 12 and 16, the level or amplitude of the detected radio frequency signal HF required to reproduce the information stored on the recording medium OD is less than the detected radio frequency signal HF required when the scanning beam is aligned at right angles. The level or amplitude of the signal HF. The tilt of the scanning beam is corrected by using the modulation signal MO, which is shown on a larger scale in Figs. 13, 15 and 17 to illustrate the principle.

According to an exemplary embodiment, a modulation signal MO is used which is a symmetrical square wave signal with 50% zero components and a frequency of 4 Hz. In this embodiment, a symmetrical square-wave signal with a 50% zero component describes a signal in which, within a period, square-wave pulses of different polarity are alternately divided by a zero signal and have the same length.

In principle, however, other signal forms which are symmetrical about the reference line and at different frequencies can also be used as modulating signal MO. The lower envelope signal lo is multiplied by the modulation signal MO on the one hand and added to the control signal on the other hand in order to vary the inclination of the scanning beam with respect to the recording medium OD. Adding the modulation signal MO to the control signal to change the tilt of the beam affects the lower envelope signal lo in a manner that will be described below in order to explain the principle of FIG. 14 .

However, since the modulation is hardly detectable when viewing the radio frequency signal HF on an oscilloscope, the above description is only theoretical. According to an exemplary embodiment, a modulation signal MO is used whose amplitude corresponds to a change of approximately 1/30 of a degree of the scanned beam or a change of 2 arc minutes of tilt of the optical axis OA of the scanned beam. Similar to FIG. 13 , the modulated signal MO shown enlarged for illustrative purposes in FIG. 15 results in lower dark values in the lower envelope curve lo of the radio frequency signal HF (shown enlarged similarly to FIG. 14 ), which Dark values are obtained with respect to deflection beyond calibration performed at right angles.

Despite the use of a symmetrical modulation signal MO, however, the effect in the lower envelope curve lo of the radio frequency signal HF remains asymmetrical or unequal as long as the scanning beam is inclined or not at a right angle. The lower envelope signal lo is asymmetrical due to the correlation with the modulating signal MO, and this asymmetry is used to control the tilt of the scanning beam.

For this, the lower envelope signal lo is multiplied by the modulation signal MO before entering the tilt controller TIER provided with the control error. When the scanning beam is aimed at the recording medium OD at right angles, as shown in Fig. 16, this results in a radio frequency signal HF having a maximum level at the maximum amplitude, resulting in a lower envelope signal lo due to maximum cancellation achieved the lowest value of .

For illustration, Fig. 16 also shows the modulation of the lower envelope signal lo, although, in practice, this is no longer observable. When the scanning beam is directed at the recording medium OD at right angles, both the positive and negative amplitudes of the modulating signal MO result in a lower dark value that is the same for both directions of the modulating signal MO, so the control The error is zero. Scan beam tilts other than 90 degrees symmetrically modulate the modulation signal MO which is added to the control signal via adder + in order to adjust the tilt of the scan beam. A control error can thus be detected even after integrating one period of the modulation signal MO.

The disadvantages of known solutions are avoided since the lower envelope signal lo is used for the tilt control and other factors which also have a negative influence on the level or amplitude of the radio frequency signal HF are excluded from the tilt control process. Scratches, fingerprints or other dirt, defects or disturbances on the surface generally reduce the degree of reflection of the optical recording medium, thus affecting in particular the level or amplitude of the upper envelope signal up and the radio frequency signal HF. Furthermore, dirt, defects or disturbances such as on the optical recording medium OD also lead to an increased error rate in the detected information signal. Since factors such as those affect the radio frequency signal HF independently of the tilt of the scanning beam, their influence is excluded from the tilt control process by using the lower envelope signal lo representing the dark value of the detected radio frequency signal HF . No additional tilt sensor is required for the tilt control, however any influence on the tilt control by other factors which influence the radio frequency signal HF independent of the tilt of the scanning beam is nevertheless largely prevented.

The envelope signals lo, up can be generated by capacitive and DC connections from the radio frequency signal HF, while it has been found advantageous to DC connect the envelope detector ENV to the photodetector. Also, as shown in Figure 1, the tilt control loop may be in the form of a digital control loop using components already available in the recording or playback device.

In the case of playback devices for optical recording media, the radio-frequency sum signal from the photodetectors A, B, C, D is used as the information signal, also called the so-called reproduced signal, after passing through a high-pass filter, the abbreviation for RF. However, the reproduced signal loses some of the characteristics which are used by the radio frequency signal HF to form the envelope curve signal lo, up. In the recording apparatus, information is written on the optical recording medium OD on which no information signal has been stored.

However, recording media OD such as these already have so-called grooves in the form of wobbled tracks even before they are recorded, and these grooves are used for recording information. The wobble track on the optical recording medium OD, which is also used to determine the position on the recording medium OD, is also detected by the scanning device PU and, similarly to the optical recording medium OD on which information has been recorded, provides a radio frequency called the wobble signal WOB Signal HF. The lower envelope curve of the wobble signal WOB is then used for tilt control in the recording device for the optical recording medium OD.

FIG. 8 illustrates a corresponding circuit structure for implementing the method. FIG. 8 differs from FIG. 1 only in that the envelope detector ENV is replaced by a wobble detector WOB. The lower envelope signal lo of the wobble signal WOB also represents the dark value of the radio frequency signal HF or the wobble signal WOB, so the method and structure can be used in the same way for recording and playback devices. The lower envelope curve signal of the radio frequency signal HF detected from the optical recording medium OD is multiplied by the modulation signal MO and integrated or low-pass filtered to form a control error corresponding to the alignment of the optical recording medium OD The error between the scanned beam and the vertical.

As shown in FIG. 1, a tilt control loop is formed between the multiplier MU, the modulator MOD and the tilt controller TIER, so that the circuit configuration hardly involves any complexity. The modulator MOD is connected to the multiplier MU and the adder +, which is connected to the output of the tilt controller TIER, while the multiplier MU, to which it is also supplied with the lower envelope signal, is connected to the input of the tilt controller TIER, as As shown in Figure 1, the output of the tilt controller TIER is connected via a digital/analog converter D/A to a scanning unit PU having means for adjusting the tilt of the scanning beam.

The embodiments described here are cited by way of example only, and those skilled in the art will be able to come up with other embodiments of the invention that remain within the scope of the invention.

Claims (11)

1. one kind about the playback of optical recording media or the method for recording unit, described playback or recording unit have the roll control system that is used for scanning beam, are wherein detected by described optical recording media and represent that the lower enveloping curve signal of radiofrequency signal of the dark value of detected radiofrequency signal is used to control.

2. the method for claim 1, wherein said radiofrequency signal is by the detected radiofrequency signal of the information tracks of optical recording media, and this radiofrequency signal is through being used as the information signal of reproduction after the high-pass filtering.

3. the method for claim 1, wherein said radiofrequency signal is the swinging signal by the detected optical recording media of described optical recording media.

4. the method for claim 1, wherein said lower enveloping curve signal are the image signals that is produced by the enveloping curve detecting device.

5. the method for claim 1, wherein before entering roll control system, with modulation signal, described modulation signal is added to the output signal from roll control system with described lower enveloping curve signal times, so that scanning beam is stated optical recording media with the right angle aligning.

6. the method for claim 1, the symmetrical square wave signal that wherein will have 50% zero-signal component is as modulation signal.

7. the method for claim 1, wherein the lower enveloping curve signal times of the radiofrequency signal that will be detected by optical recording media is with a modulation signal, and it is carried out integration or low-pass filtering, so that the formation departure, described departure is corresponding to scanning beam that points to optical recording media and any error between the vertical line.

8. one kind about the playback of optical recording media or the structure of pen recorder, described playback or pen recorder have the roll control system that is used for scanning beam, wherein the input of roll control system is connected to multiplier, the input of described multiplier is connected to the connection of generation by the lower enveloping curve signal of the detected radiofrequency signal of described optical recording media, and the input of described multiplier is connected to modulator, described modulator is connected to the output of described roll control system, and the output of described roll control system is connected to the device of the inclination that is used to change the scanning beam that points to described optical recording media.

9. structure as claimed in claim 8, wherein said modulator is a totalizer to the connection of the output of described roll control system.

10. structure as claimed in claim 8, the connection that wherein is used to produce by the lower enveloping curve signal of the detected radiofrequency signal of described optical recording media is an enveloping curve detecting device.

11. structure as claimed in claim 8, the connection that wherein is used to produce by the lower enveloping curve signal of the detected radiofrequency signal of described optical recording media is a wobble signal detector.

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